Shape memory thermal interface materials

ABSTRACT

Disclosed is a shape memory polymer (SMP) thermal interface material. The shape memory polymer may include a SMP matrix. The SMP matrix may include a liquid crystal elastomer. The SMP material may also include a thermally conductive filler embedded within the SMP matrix. The thermally conductive filler may include one or more substantially aligned subcomponents.

BACKGROUND

Aspects of the present disclosure relate to thermal interface materials;more particular aspects relate to shape memory thermal interfacematerial pads.

Thermal interface materials create a connection between a heat producingcomputing component and a heat dissipating structure to decrease thetemperature of the heat producing computing component. The thermalinterface material may dissipate heat from the heat producing computingcomponent by transferring the heat to a heat dissipating structure likea heat sink. The heat sink may be attached to the computing component ora structure comprising the computing component.

SUMMARY

Embodiments of the present disclosure include a shape memory polymer(SMP) thermal interface material (TIM). The SMP material may include aSMP matrix. The SMP matrix may include a liquid crystal elastomer. TheSMP material may also include a thermally conductive filler embeddedwithin the SMP matrix. The thermally conductive filler may include oneor more substantially aligned subcomponents.

The above summary is not intended to describe each illustratedembodiment or every implementation of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings included in the present application are incorporated into,and form part of, the specification. They illustrate embodiments of thepresent disclosure and, along with the description, serve to explain theprinciples of the disclosure. The drawings are only illustrative ofcertain embodiments and do not limit the disclosure.

FIG. 1 depicts an example liquid crystal elastomer thermal interfacematerial pad with a thermally conductive filler, according to variousembodiments of the disclosure.

FIG. 2 depicts an example shape memory liquid crystal elastomer thermalinterface material pad changing between a first state and a secondstate, according to various embodiments of the disclosure.

FIGS. 3A-3D depict an example process for attaching a heat dissipatingstructure to a circuit board using a shape memory liquid crystalelastomer thermal interface material pad, according to variousembodiments of the disclosure.

FIG. 4 depicts a flowchart of an example method for making a liquidcrystal elastomer thermal interface material pad, according to variousembodiments of the disclosure.

FIG. 5 depicts a flowchart of an example method for assembling a heatdissipating structure with a shape memory liquid crystal elastomerthermal interface material pad, according to various embodiments of thedisclosure.

FIG. 6 depicts the representative major components of an examplecomputer system, according to various embodiments of the disclosure.

While embodiments of the present disclosure are amenable to variousmodifications and alternative forms, specifics thereof have been shownby way of example in the drawings and will be described in detail. Itshould be understood, however, that the intention is not to limit thedisclosure to the particular embodiments described. On the contrary, theintention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the invention.

DETAILED DESCRIPTION

Aspects of the present disclosure relate generally to shape memorypolymers, and in particular, to using shape memory polymers to createthermal interface material pads. While the present disclosure is notnecessarily limited to such applications, various aspects of thedisclosure may be appreciated through a discussion of various examplesusing this context.

During operation, a computer chip, also sometimes referred to as acomputing chip, may generate heat. If the heat is not dissipated, thecomputer chip may reach a temperature where it automatically shuts down,where it throttles back (e.g., a CPU may run at a lower clock rate), orthe chip may become damaged. For example, a computing chip may have anautomatic shutdown enabled when the computing chip reaches a temperaturethreshold (e.g., 80° C.). Upon reaching the temperature threshold of 80°C., the computing chip may shutdown or restart to prevent damage to thecomputing chip. To prevent the buildup of heat, a heat dissipatingstructure may be thermally coupled to the computing chip.

The computing chip may be a semiconducting wafer containing circuitry,which runs computerized devices. Some examples of computing chips mayinclude, but are not limited to, Central Processing Unit (CPU) chips,Graphical Processing Unit (GPU) chips, Application Specific IntegratedCircuits (ASICs), Dual In-Line Memory Modules (DIMMs), and FieldProgrammable Gate Array (FPGA) chips, as well as custom designedcomputer chips. A heat transfer material, such as a thermal interfacematerial (TIM), may be positioned between the computing chip and theheat dissipating structure to transfer the heat from the computing chip(e.g., CPU chip) to the heat dissipating structure (e.g., heat sink). Toincrease the efficiency of a TIM, one or more factors may be considered.The factors of the TIM may include: bond line thickness, bond lineefficiency (e.g., how well the TIM connects the computer chip to theheat dissipating structure with lack of air bubbles, consistentthickness, etc.), consistency, and composition. The TIM composition maybe improved by altering the chemicals (e.g., the purity of thechemicals) within the TIM. The consistency of the TIM may be affected ifair pockets are present within the TIM. The bond line efficiency may bealtered in response to the TIM incorrectly layering on the top surfaceof the computing chip (e.g., the TIM is not consistently spread over thetop surface of the computing chip and there are ridges, gaps, etc. inthe layering). The heat transfer rate from the computer chip to the heatdissipating structure may be improved by decreasing the thickness of thebond line.

Some computing chips may have a relatively large variance (e.g., greaterthan 200 micrometers (μm) (or 0.008 inches, 8 mil)) on their surface,which may limit the ability of heat dissipating structures to removeheat from the computing chips (e.g., due to air gaps and high thermalcontact resistance). Variances such as these in the chip may be overcomeby using highly compressible TIM pads at high pressures (e.g., 50 poundsper square inch (psi)) to fill in any inconsistencies on the surface ofthe chip by compressing the TIM pad. Issues may arise when usingcompressible TIM pads with computing chips, as some computing chipmanufacturing companies recommend that a force no greater than 30-35 psishould be exerted upon the computing chip. If the TIM pad requires acompression force of 50 psi but the computing chip can only withstandforces of 35 psi, then the computing chip may be damaged during thecompression of the TIM pad. Therefore, a highly compressible TIM at therecommended 35 psi or below is desired so that the maximum gap (e.g.,distance) between the computing chip and the heat dissipating structurecan be filled (including, e.g., both a thin bond line and anyinconsistencies on the surfaces of the computing chip—heat dissipatingstructure bond).

Embodiments of the present disclosure include using shape memorypolymers (SMP) as thermal interface materials (TIM) between heatproducing computing components (e.g., computer chips, etc.) and heatdissipating structures (e.g., heat sinks, heat exchangers, etc.). TheSMP TIMs may be formed into pads that may be positioned between thecomputer chips and heat dissipating structures to fill in gaps betweenthe computer chips and heat dissipating structures, thereby improvingthe transfer of heat away from the computer chips. In some embodiments,the SMP TIM pad may be flexible and/or compressible. This may allow theSMP TIM to conform to the shape of the computing chip. In someembodiments, the SMP may be a liquid crystal elastomer (LCE) matrix,which may be formed and/or deformed to result in a thermal connection(e.g., able to transfer heat) between the computing chip and the heatdissipating structure.

Furthermore, aspects of the present disclosure may advantageouslyinclude a thermally conductive filler (e.g., carbon fibers), which maybe embedded within the LCE matrix. An LCE matrix that includes athermally conductive filler is referred to herein as a liquid crystalelastomer thermal interface material pad (LCE TIM pad). The LCE matrixmay have shape memory properties where a first shape has a first height(e.g., thickness), length, and width. A smaller height of the LCE TIMpad may result in a thinner bond line between the computing chip and theheat dissipating structure allowing for greater thermal transfer.

It is to be understood that the aforementioned advantages are exampleadvantages and should not be construed as limiting. Embodiments of thepresent disclosure can contain all, some, or none of the aforementionedadvantages while remaining within the spirit and scope of the presentdisclosure.

Shape memory TIM pads may be constructed such that they have a desiredconsistency and composition, as well as an effective bond lineefficiency (e.g., the TIM pad has to be layered consistently on thecomputing chip and is at such a thickness to promote optimal heattransfer with the heat dissipating structure) when they are createdbased on the size of the computing chip. The shape memory TIM may bemodified between one or more states (e.g., physical states such assolids, liquids, etc.) to decrease the bond line thickness between thecomputing chip and the heat dissipating structure, which may increasethe thermal dissipation of the heat from the computing chip (e.g., byincreasing the thermal conductivity or thermal diffusivity of the TIM).

The heat dissipating structure may draw the heat from the computing chipthrough the TIM to the cooler heat dissipating structure. The cooling ofthe heat dissipating structure may include passive or active cooling.Passive cooling may occur when a structure has an increased surface arearelative to the computing chip. Active cooling may occur, for example,with the use of a cooling device such as a fan or liquid cooling systemconfigured to actively cool the heat dissipating structure, which may bea heat sink (e.g., fan cooling) or a cooling plate (e.g., liquidcooling).

The SMP TIM pad may include an SMP matrix with thermally conductivefillers (e.g., conductive fibers) suspended within the SMP matrixforming shape memory TIM pads. SMPs may be “smart materials” which mayreturn to an “original” (e.g., first, un-deformed, etc.) state or shapeafter being transformed to a “deformed” (e.g., second, transformed,etc.) state or shape. The deformed state may be produced when the shapememory TIM pad is exposed to an external stimuli (e.g., a conditionchange). For example, external stimuli may include changes intemperature, light, magnetic fields, and physical stimuli, such aschanges in pressure and external forces. The SMP may include a LCE asthe smart memory matrix allowing for a reversible liquid crystalline(LC) phase transition. The LC phase transition may allow a SMP totransform between two different phases (e.g., states) based on externalstimuli. Accordingly, the SMP TIM that includes an LCE matrix may bereversibly changed between a first (e.g., original) state and a second(e.g., deformed) state using the external stimuli.

The SMP matrix may include, but is not limited to, polymers that may bereversibly altered between a first state (e.g., first shape) and asecond state (e.g., second shape) in response to external stimuli. SMPmatrices may include, for example, LCEs, thermoresponsive polymers suchas polyurethane, polyesters (e.g., polyethylene terephthalate),polyethers (e.g., polyethylene glycol), or various co-polymers (e.g.,copolyesters). In some embodiments, the SMP matrix may be physicallycross-linked linear block copolymers (e.g., polyurethanes) with ionic ormesogenic components. In various embodiments, various shape memorypolymers may be utilized as matrices along with the thermally conductivefillers to create shape memory TIM pads.

In various embodiments, the deformation of the SMP TIM pad may includeusing a first frequency or wavelength of light. The wavelength may bedetermined based on the composition of the SMP being used as the SMPmatrix. For example, a LCE may be shaped and maintained at the deformedshape by exposing the LCE to 280 nm ultraviolet light. The ultravioletlight (100-400 nm) may cure the SMP TIM pad at the deformed shape.

In some embodiments, the shape memory polymer thermal interface materialmay include a shape memory polymer matrix. The shape memory polymermatrix may include a liquid crystal elastomer. Additionally, a thermallyconductive filler may also be embedded within the shape memory polymermatrix. The thermally conductive filler may include substantiallyaligned subcomponents. In some embodiments, the subcomponents mayinclude electromagnetically responsive particles, fibers, or anycombination of particles and fibers substantially aligned in a firstdirection. In some embodiments, the electromagnetically responsiveparticles, fibers, and/or combination of particles and fibers may beconfigured to deform to a second direction.

For example, the particles and/or fibers in the thermally conductivefiller may be oriented in the SMP TIM pad such that the particles andfibers are substantially pointed left-to-right (e.g., aligned in a firstdirection). The particles and/or fibers may then have a pressure (orheat) applied to them and deform to an up-and-down position (e.g., asecond direction). In some embodiments, the thermally conductive fillerin the SMP TIM pad may be configured to deform its particles and/orfibers in such a way as to relieve stress and pressure from thecomputing chip.

In some embodiments, the shape memory polymer matrix may be configuredto expand anisotropically. In other embodiments, the shape memorypolymer matrix may be configured to expand isotropically. In someembodiments, the shape memory polymer matrix includes one or morecross-linking polymer networks.

In some embodiments, a shape memory polymer matrix and a thermallyconductive filler may be mixed to create a shape memory polymer mixture.The shape memory polymer mixture may be extruded through a die. Thethermally conductive filler in the shape memory polymer mixture may bealigned in substantially the same direction. The shape memory polymermixture may be cured at a first temperature (e.g., a curingtemperature). The curing may cause the shape memory polymer mixture toharden. As used herein, hardening includes increasing the viscosity ofthe shape memory polymer mixture such that the hardened shape memorypolymer mixture is capable of being cut into individual pads thatsubstantially retain their shape when not subjected to externalpressures or elevated temperatures. The shape memory polymer mixture maythen be sliced into one or more shape memory polymer thermal interfacematerial pads.

In some embodiments, the shape memory polymer mixture may be heated to asecond temperature and may be held at the second temperature whilepassing through the die during extrusion. In some embodiments, thesecond temperature may be above the first temperature (e.g., above thecuring temperature and may cause the shape memory polymer mixture tobecome pliable and malleable, such as in a highly viscous liquid state).

In some embodiments, the thermally conductive filler may beferromagnetic. In some embodiments, in order to substantially align thethermally conductive filler in the same direction, a direction ofthermal conduction (e.g., a direction that the user wants the heat totransfer) may be determined (e.g., it must be determined on which sidethe heat sink will be bonded to the SMP TIM pad, in order for the fillerto direct the heat generated by the computing chip away from the chipand towards a heat dissipating structure). In some embodiments, afterdetermining a direction of thermal conduction, a magnetic field may beapplied to the thermally conductive filler. The magnetic field mayorient the filler in the direction of thermal conduction.

For example, a thermally conductive filler may contain iron fibers andit may be determined that a heat sink will be applied to an areadirectly atop the SMP TIM pad (e.g., which includes the thermallyconductive filler). A magnetic field may be applied to the thermallyconductive filler. The magnetic field may have a strong magnetic pullnearest the top of the thermally conductive filler, inducing the ironfibers to align in substantially the same direction (e.g., pointingupwards).

In some embodiments, the thermally conductive filler may besubstantially aligned in the same direction during extrusion. Forexample, a thermally conductive filler may include two or more particlesor fibers that are initially aligned in a non-uniform way (e.g., eachfiber is aligned in a different orientation). The thermally conductivefiller (while mixed in the shape memory polymer mixture) may be extrudedthrough a die and the fibers in the thermally conductive filler may bephysically (e.g., forcibly) aligned in a substantially uniformdirection. For example, the die may include a sieve or sieve-likestructure. As the mixture is extruded through the die, the thermallyconductive filler (e.g., the particles or fibers) may interact with thesieve such that the filler is physically aligned in substantially thesame direction.

In some embodiments, to cure the shape memory polymer mixture, the shapememory polymer mixture may be heated to a first temperature. In someembodiments, the shape memory polymer mixture may be held at the firsttemperature for a predetermined time. The predetermined time may bedetermined by the physical properties of the shape memory polymermixture. In some embodiments, the shape memory polymer mixture may becooled in order to harden and finish curing.

For example, a shape memory polymer mixture may be a mixture ofpolyurethane and silver fibers. It may be determined that the mixture ofpolyurethane and silver fibers substantially harden with heated to atemperature of 100° C. and held at that temperature for 20 minutes. Themixture may be held at 100° C. for 20 minutes and let cooled for anhour. Upon cooling, the mixture may be substantially hardened comparedto the mixture being uncured. The mixture may then be sliced into SMPTIM pads.

FIG. 1 depicts an example SMP TIM pad 100, according to embodiments. TheSMP TIM pad 100 may include a SMP matrix 102 (e.g., an LCE) and athermally conductive filler 104 (e.g., carbon fibers). The thermallyconductive filler 104 may be suspended within the SMP matrix 102 duringa mixing operation. The mixture of the thermally conductive filler andthe SMP matrix may then be extruded through a die and cured to solidifythe SMP matrix. Before extruding, the thermally conductive filler 104may be arranged so the thermally conducive filler (e.g., the conductiveparticles, fibers, or particles and fibers of the thermally conductivefiller) are aligned substantially in a first direction.

In various embodiments, the thermally conductive filler may includeparticles, which may be dispersed substantially uniformly within the SMPmatrix. The SMP TIM may be extruded through a die to create a SMP TIMblock, which may be sliced into one or more SMP TIM pads. The extrudedand sliced SMP TIM pad may have a first shape with a first length(illustrated as the X-axis), a first width (illustrated as the Y-axis,extending into the page), and an overall height (illustrated as the Zaxis). The block of SMP TIM pads may be sliced (e.g., along theXY-plane- to a first height to create a SMP TIM pad 100 at a firstheight or at a first state (e.g., non-deformed state).

In various embodiments, the thermally conductive filler may be (orinclude) thermally conductive particles. The thermally conductiveparticles may include non-fibrous chemical particles or molecules thathave heat-transferring properties. Thermally conductive particles mayinclude chemical particles such as beryllium oxide, aluminum nitride,aluminum oxide, silver, boron nitride, or zinc oxide. These thermallyconductive particles may be used alone as thermally conductive fillers,or in combination with a thermally conductive filler of a fibrousnature.

For example, carbon fibers and beryllium oxide may be added to the SMPmatrix and utilized as a thermally conductive filler. Any combination ofone or more thermally conductive particles and/or one or more thermallyconductive fibers may be used as the thermally conductive filler. Insome embodiments, the thermally conductive filler may includeelectromagnetically responsive particles that may be substantiallyaligned in a first direction at a curing temperature. Theelectromagnetically responsive particles may be substantially aligned byholding a magnet over the SMP TIM pad while the SMP TIM pad, whichincludes the thermally conductive filler, is at the curing temperature(e.g. the temperature at which the SMP TIM is hardening).

For example, an SMP TIM may be produced by combining a thermallyconductive filler that includes metallic particles and an LCE. The SMPTIM material (e.g., the thermally conductive filler and the LCE) may bemalleable and extruded and sliced into a wafer. To harden the SMP TIMmaterial, the wafer may be heated or cooled to a curing temperature,while curing the wafer, a magnet may be held directly over the wafer.The magnet may perpendicularly align all the metallic particles found inthe wafer. In some embodiments, the magnet may make contact with thewafer. In some embodiments, the particles may not be perpendicularlyaligned, they may be substantially aligned in any direction.

The SMP matrix 102 may consist of cross-linked polymer networks, whichmay form a first size or state (e.g., an un-deformed state or anoriginal state) of the SMP TIM pad. The first state of the SMP TIM padmay be altered to a deformed state, and then reformed back to the firststate (e.g., see FIG. 2). Each polymer molecule (or polymer chain) of across-linked polymer network may be bonded with covalent or ionic bondsto another polymer chain or molecule within the matrix. Thesecross-linked polymer networks may define the first shape of the SMP TIMpad and allow for a reformation of the SMP TIM pad to the first stateafter a deformation.

The SMP matrix may be deformed by a condition change (e.g., externalstimuli) such as temperature. In some embodiments, the SMP matrix mayhave a reformation temperature (e.g., first temperature), causing theSMP TIM pad to reform to a non-deformed state (e.g., first state, orcompressed state, or original state) from a deformed state (e.g., secondstate, expanded state, or altered state). For example, the reformationtemperature may be 100° C., and when an SMP TIM pad in a second state isexposed to the reformation temperature, the SMP TIM pad may compress tothe first state.

In another example, an SMP TIM may be bonded between a computer chip anda heat dissipating structure. The computer chip may be a part of andused by a high-performance computer. While being used by thehigh-performance computer, the computer chip may increase in heat (e.g.,from room temperature 21° C. to 50° C.). The heat generated by thecomputer chip may transfer into the bonded SMP TIM and the SMP TIM mayhave a transition state temperature of 48° C. The SMP TIM may transitionfrom a solid to a high viscosity liquid (e.g., from a compressed firststate to an uncompressed second state), the liquid state of the SMP TIMmay allow for greater heat transfer between the computer chip and theheat dissipating structure (e.g., by increasing surface area, thermalconductivity, thermal conductivity, etc.). In some embodiments, afterthe SMP TIM has sufficiently cooled the computer chip by being a thermalmedium to transfer heat to the heat dissipating structure and thetemperature has dropped below the SMP TIM's transition statetemperature. The SMP TIM may return to the compressed first state (e.g.,solid state). In some embodiments, in addition to the heat transferproperties of the SMP TIM pad, the SMP TIM pad may contract in thecompressed first state to avoid excessive normal force being applied tothe computer chip.

In some embodiments, the SMP matrix may have a deformation temperature(e.g., second temperature, transition state temperature, etc.) and whenthe SMP matrix is heated to the deformation temperature, the SMP matrixmay expand. The SMP TIM pad may deform to a deformed state (e.g., secondstate) when it is heated to the deformation temperature. For example,the deformation temperature may be 125° C., and when an SMP TIM pad inthe first state is exposed to the deformation temperature, the SMP TIMpad may deform (e.g., expand) to the second state.

The SMP TIM pad 100 may also be viewed as a cross section of a SMP TIMblock that expands on the Z-axis. The SMP TIM block may includethermally conductive fillers that extend along the Z-axis for theconduction of heat from a computing chip to a heat dissipatingstructure. When the SMP TIM block is sliced along the XY-plane, thethermally conductive filler may be aligned (e.g., oriented) such thatthe heat may flow in the direction of the orientation of the thermallyconductive filler from the bottom to the top in the Z-axis direction. Invarious embodiments, the thermally conductive filler may be partiallyaskew from perpendicular to the XY-plane (via the combined X-axis andY-axis) but still allow heat to flow through the thermally conductivefiller to the heat dissipating structure.

The thermally conductive filler 104 may perform the heat dispersionfunctionalities of the SMP TIM pad 100. For example, the thermallyconductive filler 104 may be selected from the group consisting ofcarbon fibers, carbon nanotubes, silicon carbide, beryllium oxide,aluminum nitride, aluminum oxide, silver, boron nitride, zinc oxide,etc. The thermally conductive filler 104 may be suspended within the SMPmatrix 102 and aligned such that thermally conductive filler issubstantially in a first orientation (e.g., a majority of the thermallyconductive fibers may be within ±30° of perpendicular to the XY-plane).For example, the first orientation of the SMP TIM pad 100 may be alongthe Z-axis.

In various embodiments, the heat dispersion functionalities of thethermally conductive fibers may be increased or decreased according tothe bond line, the concentration of thermally conductive filler comparedto the SMP matrix, and/or the alignment of the thermally conductivefiller. A decrease in the bond line (e.g., the bond thickness betweenthe computing device and the heat dissipating structure) may increasethe heat dispersion functionality of the SMP TIM pad due to thedecreased distance the heat will have to travel before reaching the heatdissipating structure. Also, an increase in the concentration (oramount) of thermally conductive filler may increase the heat dispersionfunctionality of the SMP TIM pad due to the increase in thermaltransferring material of the SMP TIM pad. The alignment of the thermallyconductive filler may allow for an increased heat dispersionfunctionality of the SMP TIM when the thermally conductive filler is ata substantially perpendicular orientation with regard to the computingchip and heat dispersal device (e.g., due to particle lattices of thethermally conductive filler in the perpendicular orientation negligiblyreflecting and deflecting heat in a direction away from the heatdissipating structure).

FIG. 2 depicts an example shape memory shape memory polymer thermalinterface material pad changing between a first state and a secondstate, according to embodiments. A SMP TIM pad may be altered from anoriginal state 210 (e.g., a first state, compressed state) SMP TIM padto a deformed state 212 (e.g., a second state) SMP TIM pad. The SMP TIMpad may be exposed to one or more condition changes to alter the stateof the SMP TIM pad. For example, the original state 210 may be exposedto a first condition change 220 (e.g., expansion condition change, suchas an elevated temperature). This may cause the SMP TIM to transitionfrom the original state 210 (e.g., first state) to the deformed state212 (e.g., second state).

Likewise, the SMP TIM pad may be transitioned from the second state tothe first state. For example, the SMP TIM pad in a deformed state 212)may be exposed to a second condition change 222 (e.g., a compressioncondition change, reformation condition change, such as a lowertemperature). This may cause the SMP TIM to transition from the deformedstate 212 (e.g., second state) to the original state 210 (e.g., firststate).

In various embodiments, the expansion condition change of the SMP TIMpad may be done using a method called cold drawing. The cold drawingprocesses may alter the SMP TIM pad to the deformed state mechanicallywithout altering the SMP TIM pad to a second temperature. The colddrawing process may be an expansion processes and may act as a firstcondition change for the SMP TIM pad. The cold drawing process may beperformed by mechanical means using an expansion apparatus including afirst plate and a second plate configured to exert an expansion force onthe SMP TIM pad.

The expansion condition change for an expansion condition change 220 mayalso be an expansion force being exerted on the original state 210. Theoriginal state 210 may be deformed using mechanical means to exert aforce on the SMP TIM pad. By mechanically expanding the original state210 to a desired height, the deformed SMP TIM pad may then be heated todefine a second state (e.g., deformed state 212). For example, the SMPTIM pad may be attached to two opposing plates. The first plate andsecond plate may include an attachment force (e.g., vacuum suction) thatattaches to either side of the height (e.g., on opposite sides) of theSMP TIM pad. The plates may then pull away from each other, putting theSMP TIM pad in tension and causing the SMP TIM pad to transition to thedeformed state 212. The SMP TIM pad may additionally be heated aboveoperating temperatures of the computing chip (e.g., 120-200° C.) totransition the SMP TIM pad to the deformed state. In variousembodiments, the deformation temperature may be within a range of130-190° C. In other embodiments, the deformation temperature may bewithin a range of 150-170° C. Because the SMP TIM pad was strained whileat a heightened temperature, the SMP TIM pad may retain its shape (e.g.,stay in the deformed state), even after the mechanical strain is relaxedand the SMP TIM pad returns to room temperature. For example, the SMPTIM pad may be expanded from 1 mm to about 1.5 mm and then heated toabout 120° C. to maintain the shape of the SMP TIM pad in the deformedstate.

In the deformed state 212, the SMP TIM pad may be greater in size in atleast one dimension (e.g., greater in height) than while in the originalstate 210. For example, the SMP TIM pad may have a height of 1 mm in theoriginal state 210. The SMP TIM pad may then be exposed to an expansioncondition change for heating the SMP TIM pad from room temperature to125° C., at a rate of about 2° C. per minute, to cause the expansioncondition change altering the height of the SMP TIM pad to 1.5 mm. TheSMP TIM pad may then be held at the expansion trigger temperature for aperiod of time (e.g., one minute) then cooled to a third temperature(e.g., room temperature (21° C.)), at about 1° C. per minute to maintainthe deformed state.

In an additional example, the SMP TIM pad may be in a deformed state andmay have a height of 1.5 mm. The SMP TIM pad may then be exposed to areformation condition change (e.g., a reformation condition change 222,FIG. 2) of heating the SMP TIM pad in the deformed state to areformation temperature. For example, the reformation temperature may bewithin a range of 80-120° C. In the example, the reformation temperaturemay be 100° C. After heating the SMP TIM pad to the reformationtemperature of 100° C., the SMP TIM pad may be held at 100° C. for aperiod of time and then cooled at about 2° C. per minute to roomtemperature, to cause the reformation condition change altering theheight of the SMP TIM pad to 1 mm. The SMP TIM pad may be held at thereformation condition change temperature until the SMP TIM padcompresses to the 1 mm height, the SMP TIM pad may then be cooled toroom temperature (or some other operating temperature) to maintain theoriginal state of the SMP TIM pad.

In various embodiments, the changing of the SMP TIM pad from the firststate to the second state may likewise change the width and length ofthe SMP TIM pad. This may be because the SMP TIM pad material mayundergo or experience isotropic shape changes (i.e., uniform in alldirections). If the SMP TIM pad changes shape isotopically, the lengthand width of the SMP TIM pad may also be increased when transitioningthe SMP TIM pad from the first state to the second state. For example,the SMP TIM pad in the original state may be 30 mm in width, 30 mm inlength, and 1 mm in height. When the SMP TIM pad transitions to thesecond state, it may expand in all directions by 5% in size.Accordingly, the dimensions of the SMP TIM pad in the second state SMPTIM may be 31.5 mm in width, 31.5 mm in length, and 1.05 mm in height.

In various embodiments, the SMP TIM pad may expand anisotropically or inan anisotropic direction (i.e., directionally dependent, not isotropic).The anisotropic expansion may allow the SMP TIM pad to expand only inheight, only in two directions, and/or at different rates, depending onembodiments or matrices of the SMP. The anisotropic expansion of the SMPTIM pad may result in the SMP TIM pad only increasing in height whileremaining the same in width and length. For example, anisotropicexpansion of the SMP TIM pad may result from a SMP TIM pad in anoriginal state of 30 mm in width, 30 mm in length, and 1 mm in height toa deformed state of 30 mm in width, 30 mm in length, and 1.5 mm inheight.

FIGS. 3A-D depict an example process of attaching a heat dissipatingstructure to a circuit board using a shape memory polymer thermalinterface material pad, according to embodiments of the presentdisclosure. A heat dissipating structure 350 may be attached to acircuit board 300 for a heat dispersal of a computing chip 340 that iscommunicatively coupled to the circuit board and thermally coupled tothe heat dissipating structure via a SMP TIM pad. An SMP TIM pad in thedeformed state 312 (e.g., second state) may be placed between thecomputing chip 340 and the heat dissipating structure 350 (e.g., on thebare die of the computing chip 340 opposite the printed circuit board300). The deformed state 312 of the SMP TIM pad may be a result of theSMP TIM pad being deformed (e.g., the expansion condition change 220, ofFIG. 2) from an original state (e.g., the original state 210, of FIG.2). The deformed state SMP TIM pad 312 may then be subjected to a firstcondition change by heating the SMP TIM pad to a compression conditionchange temperature to compress the SMP TIM pad to the original state310. The heat dissipating structure 350 may then be fastened to thecircuit board 300 using one or more fasteners 360.

In FIG. 3A, a SMP TIM pad in a deformed state 312 is positioned on acomputing chip 340, wherein the computing chip is communicativelycoupled to a printed circuit board 300. In some embodiments, the SMP TIMpad may be in a deformed state before being placed on the chip 340. Thedeformed SMP TIM pad 312 may be obtained by subjecting a SMP TIM pad ina relaxed (e.g., un-deformed) state to an expansion condition. Forexample, a tensile mechanical load may be used to expand the SMP TIMpad. The tensile load may be applied by attaching metal plates toopposite ends of the SMP TIM pad, and then applying an expansive force(e.g., deformation force) that causes the plates to move away from eachother, putting the SMP TIM pad in tension. The tensile load may beapplied while the SMP TIM pad is at a deformation temperature. Thetensile load may be maintained for a predetermined period of time thatcauses the SMP TIM pad to retain its deformed shape. The magnitude ofthe tensile load, the elevated temperature, and the period of time maybe based on the particular LCE material of the SMP TIM pad. The SMP TIMpad may then be allowed to cool and the mechanical load may be relaxed.

In various embodiments, the SMP TIM pad may be deformed after beingplaced on the chip 340. For example, the SMP TIM pad in the originalstate may be attached (e.g., mated) to the chip. The SMP TIM pad maythen be exposed to an expansion condition change temperature (e.g., anexpansion trigger temperature of 125° C., FIG. 2).

In FIG. 3B, a heat dissipating structure 350 is positioned above thecomputing chip 340 with the deformed state SMP TIM pad 312 positionedbetween the computing chip and the heat dissipating structure. The heatdissipating structure 350 may include a first surface in contact withthe SMP TIM pad, and one or more other surfaces for cooling the heatdissipating structure. In various embodiments, the first surface of theheat dissipating structure 350 and/or the surface of the computing chip340 in contact with the SMP TIM pad may be inconsistent and require afirst pressure to be exerted on the SMP TIM pad to fill in theinconsistencies.

In FIG. 3C, the SMP TIM pad may be altered from the deformed state to anoriginal state 310. A loading force (e.g., compressive load) may beapplied to the heat dissipating structure 350 by a compression element320. The loading force may be based on the materials used, the allowableload of the chip, and the thermal resistance requirements of theintended application. The condition change may be a result ofcompressing the heat dissipating structure 350, using a compressionelement 320 (e.g., a hydraulic press), into the computing chip 340 andthe circuit board 300, and heating the deformed SMP TIM pad. Thedeformed SMP TIM pad may then return (shrink) to the original state SMPTIM pad 310. The original state SMP TIM pad 310 may create a thinnerbond line between the heat dissipating structure 350 and the computingchip 340 when compared to the deformed state of the SMP TIM pad (e.g.,deformed SMP TIM pad 312 of FIG. 3B). While the compression force isbeing applied, the SMP TIM pad may be heated by a heating element 330.The heating element 330 may reform the SMP TIM pad to the originalstate. For example, the heating element may heat the SMP TIM pad to 100°C. to trigger the compression condition change altering the SMP TIM padto the original state 310. The original state 310 may create a thinnerbond line between the heat dissipating structure 350 and the computingchip 340 when compared to the deformed state 312 of the SMP TIM pad(e.g., deformed SMP TIM pad 312 of FIG. 3B).

For example, a deformed SMP TIM pad at 1.5 mm may undergo a compressionchange to the original state of the SMP TIM pad using a hydraulic pressand a forced air heating element. The hydraulic press may apply a firstforce to the SMP TIM pad and compress the SMP TIM pad, and the forcedair heating element may heat the SMP TIM pad to 100° C. causing acompression condition change and shrinking the SMP TIM pad to theoriginal state at 1 mm.

In various embodiments, thermal property requirements of the SMP TIM padmay be determined based on the type of computing chip and the type ofheat dissipating structure. For example, if the computing chip can onlywithstand 30 psi of compressive force, then the thermal propertyrequirements may require a thinner SMP TIM pad before compression and aload force of less than 30 psi to the SMP TIM pad.

The contraction of the SMP TIM pad to the original state 310 from thedeformed state SMP TIM pad 312 may reduce the distance between the heatdissipating structure 350 and the computing chip 340. The reduction ofthe distance between the heat dissipating structure 350 and thecomputing chip 340 may increase the thermal dissipation from the chip tothe heat dissipating structure. Increasing the thermal dissipation mayreduce the operating temperature of the computing chip 340. For example,a computing chip may operate under a first computational load at 55° C.with a SMP TIM pad height of 1.5 mm, but operate at 50° C. under thefirst computational load with a SMP TIM pad height of 1 mm due to theincreased thermal dissipation.

The compression of the SMP TIM pad 310 using the compression element320, along with the flexibility of the SMP TIM pad, may result in theSMP TIM pad filling any inconsistencies of the computing chip 340 and/orthe heat dissipating structure 350. For example, if the computing chip340 has a 200 μm inconsistency protruding from the top surface of thechip in contact with the SMP TIM pad, the SMP TIM pad may flex to fillin the inconsistency while remaining in contact with the top surface ofthe chip. In another example, the computing chip may have a 100 μm voidon the top surface of the chip. The SMP TIM pad may flex and fill in the100 μm void in the top surface of the chip.

In FIG. 3D, the heat dissipating structure 350 may be fastened to thecircuit board 300 using one or more fasteners 360. Examples of fasteners360 may include CPU mounts, screws, a latch system, pressure mountclips, pins, springs, spring clips, bolts, or any other means offastening devices. The fasteners may maintain a compressive pressure onthe heat dissipating structure, forcing the original state SMP TIM pad310 into the computing chip 340. The compressive pressure exerted by thefasteners may be used to maintain the contact between the original stateSMP TIM pad 310, the computing chip 340, and the heat dissipatingstructure 350, fixing the bond lines.

FIG. 4 depicts a flowchart of an example method 400 for making a shapememory polymer thermal interface material pad, according to embodimentsof the present disclosure. The method 400 may include a process for theproduction of a SMP TIM pad at a first state and size. The SMP TIM padmay have a first size including a first length, width, and height.

In operation 402, SMP components and a thermally conductive filler maybe mixed together to create a TIM solution or mixture including an SMPmatrix and the thermally conductive filler. In some embodiments, the SMPcomponents may include a LCE. The SMP mixture may be created by mixing afirst quantity of the LCE components with a second quantity of thermallyconductive fillers. The LCE components may be mixed within a containerat a determined mixing temperature and oscillation speed. For example, aSMP may be an LCE and a thermally conductive filler may be carbonfibers. The LCE and carbon fibers may be measure in a 2:1 ratio andmixed in a continuous stirred-tank reactor (CSTR). The LCE and carbonfibers may be mixed in the CSTR at a temperature that puts the LCE at aviscosity that allows for relatively easy mixing (as compared to a highviscosity that may hinder the stirring component of the CSTR). Invarious embodiments, one or more different thermally conductive fillersmay be used within the SMP TIM mixture.

In operation 404, the thermally conductive filler of the SMP TIM mixturemay be aligned in a particular orientation (e.g., such that the fibersgenerally are aligned in the same or substantially similar direction).The thermally conductive filler or fibers (e.g., thermally conductivefiller 104, FIG. 1) of the SMP TIM may be aligned such that thethermally conductive filler may direct the heat generated from the chip,through the SMP TIM pad, to the heat dissipating device. The thermallyconductive filler may be oriented in a second direction relative to afirst orientation of the extrusion die. In various embodiments, amagnetic field may be applied to the SMP TIM mixture to align thethermally conductive filler.

For example, a user may determine that the direction of heat transferwill be going from left to right by having the left surface of the SMPTIM pad touching a computing chip and the right surface of the SMP TIMpad touching a heat sink. The user may substantially align the thermallyconductive filler in the SMP TIM mixture during extrusion in aleft/right orientation so that the SMP TIM pad may attach to thecomputing chip and heat sink and direct heat from left to right.

In operation 406, the SMP mixture may be extruded. The SMP mixture maybe extruded though a die having a first length and a first width. Thedie may produce a SMP TIM brick of the first length and first width. Theextrusion die may be oriented in a first orientation relative to asecond orientation of the thermally conductive filler. For example, theextrusion die may be oriented in a first direction substantiallyperpendicular to the orientation of the thermally conductive filler.

In some embodiments, operations 404 and 406 may not be distinctoperations. For example, the extrusion process may also cause thethermally conductive filler to align in substantially the samedirection. For example, a die used during extrusion may includesieve-like structure. As the SMP TIM mixture is extruded through thedie, the thermally conductive filler (e.g., the particles or fibers) inthe SMP TIM mixture may interact with the sieve such that the filler isphysically (e.g., forcibly) aligned in substantially the same direction.

In operation 408, The SMP TIM brick may be cured at a first temperaturefor a first time. The SMP TIM brick may be cured to maintain the firstlength and width of the SMP TIM brick. By curing the SMP TIM brick, theSMP TIM brick may maintain its shape before and during slicing to createa SMP TIM pad of a first length, a first width, and a first height. Forexample, the SMP TIM brick may be cured at 170° C. at a time of sixhours. In various embodiments, the SMP TIM brick may be cured at a firsttemperature, wherein the first temperature is the compression statetemperature. The original state (e.g., first state) (e.g., originalstate 210, FIG. 2) temperature may cause the SMP TIM to return to theoriginal state after being deformed to a second state (e.g., deformedstate 212, FIG. 2).

In some embodiments, the curing temperature and/or time for curing maybe dependent on the selected materials. For example, one SMP in a SMPTIM mixture may deform at a temperature of 10° C. after 30 minutes,therefore the curing may be done at a temperature lower than 10° C. orat a time less than 30 minutes. However, another SMP in another SMP TIMmixture may cure at 10° C. after one hour without any deformation ordamage to the SMP. In some embodiments, the curing may be done at acontrolled humidity. In some embodiments, the curing may be done at acontrolled pressure.

In operation 410, the SMP TIM brick may be placed under a first load andprepared for slicing. The first load may compress the height of the SMPTIM pad before slicing. In various embodiments, the compression of theSMP TIM brick may match the compression of the SMP TIM pad during theassembly of the heat dissipating structure to the circuit board. Forexample, the SMP TIM brick may be compressed by 30 psi, before andduring slicing, and the SMP TIM pad in the original state may becompressed to 30 psi when being assembled.

In various embodiments, during the compression, the SMP TIM brick mayalso be heated to a reformation condition change temperature. Thereformation condition change temperature may define a first state (e.g.,original state, or compressed state) of the SMP TIM pad after slicing.The original state of the SMP TIM pad may also be formed and reshapedfrom a second state (e.g., deformed state, or expanded state) afterbeing exposed to the reformation condition change temperature.

In operation 412, the SMP TIM brick may be sliced. While under the firstload, the SMP TIM brick may be sliced into one or more SMP TIM pads. TheSMP TIM pads obtained from slicing may be prepared as original state SMPTIM pads (e.g., original state 210 FIG. 2). The SMP TIM pad may besliced to a first width. For example, a SMP TIM brick may be 30 mm inwidth, 30 mm in length, and may be sliced to 1 mm in height. Theoriginal state SMP TIM pads may be used on the assembly (e.g.,attachment) of a heat dissipating structure to a circuit board that iscommunicatively coupled to a computing chip (e.g., as shown in FIGS.3A-D).

In some embodiments, the method 400 or any of the other methodsdisclosed in the disclosure may support the SMP TIM being generated interms of the method 400 (e.g., the present disclosure includes a productgenerated by performing the steps of method 400). That is, the SMP TIMmay be a product that derives its novel properties from the uniqueprocess described in the method 400 or from any combination of the othermethods disclosed. For example, the SMP TIM may derive the uniqueproperty of increased thermal transfer by inclusion of operation 404 inwhich the carbon fibers are aligned. The above is not to be limiting orcontrolling, only an example of how the SMP TIM disclosed may bedescribed in terms of the method used to generate the SMP TIM.

FIG. 5 depicts a flowchart of a method 500 for assembling a heatdissipating structure using a shape memory polymer thermal interfacematerial pad, according to embodiments. The assembly of the heatdissipating structure may include a computing chip (e.g., computing chip340, FIG. 3A), an SMP TIM pad (e.g., deformed SMP TIM pad 312, FIG. 3A),a heat dissipating structure (e.g., heat dissipating structure 350, FIG.3B), a circuit board (e.g., circuit board 300, FIG. 3A), and one or morefasteners (e.g., fasteners 360, FIG. 3D). The heat dissipating structuremay be attached to the circuit board to dissipate heat generated from acomputing chip. The computing chip may be communicatively coupled to thecircuit board, and thermally coupled with the heat dissipating structurewith a SMP TIM pad positioned between the computing chip and the heatdissipating structure.

The method 500 may begin at operation 502 where a shape memory polymerthermal interface material pad, for example an LCE TIM pad, may bedeformed to a second state (from a resting/first/original state). Forexample, the SMP TIM pad may be heated to a second temperature (e.g., anexpansion temperature that is above the resting/room temperature of theSMP TIM pad) of 125° C. to change the SMP TIM pad from a first state(e.g., original state 210, FIG. 2) of 1 mm thickness to the deformedstate (e.g., second state) of 1.5 mm thickness. The deformed state SMPTIM pad may then be positioned on a first (e.g., upper) face of thecomputing chip.

In operation 504, the deformed SMP TIM pad may be mated on the firstface of a computing chip. After deformation, the SMP TIM pad may bepositioned on the computing chip, above the top surface of the computingchip. The deformed SMP TIM pad may provide a thermal conductivity“bridge” between the computing chip and the heat dissipating structuredistributing heat generated from the computing chip to the heatdissipating structure. The SMP TIM pad may maintain the deformed stateduring operation 504.

In operation 506, a heat dissipating structure is mated to the SMP TIMpad that was previously mated to the computing chip. The heatdissipating structure may be positioned above the SMP TIM pad oppositeof the computing chip mated to the SMP TIM pad. The heat dissipatingstructure may be placed opposite of the computing chip to dissipate theheat from the computing chip. The heat dissipating structure may not bepressed into the SMP TIM pad and may be readjusted until a loading forceis applied.

In some embodiments, operations 504 and 506 may be performed in thealternative order, or simultaneously. For example, in some embodimentsthe SMP TIM pad may be mated to the heat dissipating structure. The heatdissipating structure may then be placed on the computing chip such thatthe SMP TIM pad is mated to a surface of the computing chip. As usedherein, mating include attaching the SMP TIM pad to a surface (e.g.,using an adhesive or other mechanical means), as well as simply placingthe SMP TIM pad into contact with the surface. For example, as usedherein, mating may include simply placing the SMP TIM pad on the die ofa computing chip such that they physically touch.

In operation 508, a loading force is applied to the SMP TIM pad. Theloading force (e.g., compressive pressure) may be applied through theheat dissipating structure to compress the SMP TIM pad into the heatdissipating structure and the computing chip. In various embodiments,the loading force may be applied to the SMP TIM pad or the computingchip. The loading force may cause the SMP TIM pad to deform and fill inany gaps, or voids, in the surface(s) of the computing chip and/or theheat dissipating structure, or to cover any abscesses or protrusions onthe surface of the heat dissipating structure and/or the computing chip.During the application of the loading force, any fasteners may remainfree and may not be attached to the circuit board. In variousembodiments, the fasteners may be used to apply the loading force uponthe SMP TIM pad. The loading force applied to the SMP TIM pad may alsoassist in the alteration of the SMP TIM pad from the deformed state tothe original state in operation 508.

In operation 510, the SMP TIM pad may be heated to trigger shrinkage.During the application of the loading force, the SMP TIM pad may beheated to a first temperature (e.g., reformation temperature) to triggera reformation condition change of the SMP TIM pad returning the SMP TIMpad to the original state (e.g., non-deformed state). In variousembodiments, the heating may be applied after the loading force isapplied and removed. Shrinking the SMP TIM pad may reduce the distancebetween the computing chip and heat dissipating structure, and mayincrease the thermal conductivity (e.g., may cause the thermallyconductive filler to move closer together).

In some embodiments, the SMP TIM pad may be heated with a heatingelement, which may be configured to provide a uniform heat throughoutthe SMP TIM pad. For example, the SMP TIM pad in the deformed state maybe positioned between a heat dissipating structure and computing chip.The deformed state SMP TIM pad may be heated using a heating element tothe compression temperature of 100° C. to trigger a compression of theSMP TIM pad to the original state of 1 mm in height.

In operation 512, the heat dissipating structure may be fastened to thecircuit board. After returning the SMP TIM pad to the original state,the heat dissipating structure may be fastened to the circuit board tomaintain the position of the heat dissipating structure above thecomputing chip with the SMP TIM pad in between. The fastening of theheat dissipating structure may include one or more fasteners or afastening device capable of maintaining a relatively consistent pressureon the heat dissipating structure to hold the heat dissipating structurein place.

In various embodiments, the compressive pressure may be exerted thoughthe heat dissipating structure, into the SMP TIM pad, by using thefasteners of the heat dissipating structure. The compressive pressurefrom the fasteners may compress the SMP TIM pad in a similar manner whencompared to a compressive pressure exerted by a compressive element(e.g., compressive element 320 shown in FIG. 3C). The SMP TIM pad maythen be heated by the heating element to trigger a shrinkage of the SMPTIM pad to the original state. The fasteners may then be tightened toexert a second pressure on the SMP TIM pad though the heat dissipatingstructure, and the fasteners may also hold the heat dissipatingstructure in place above the computing chip.

Some embodiments of the present disclosure may include a method forusing a TIM pad. A shape memory polymer (SMP) TIM pad may be deformed toa deformed SMP TIM pad. The deformed SMP TIM pad may be mated to a firstsurface of a computing chip. A heat dissipating structure may be matedto the deformed SMP TIM pad opposite of the first surface of thecomputing chip. A loading force may be applied to the SMP TIM pad. Thedeformed SMP TIM pad may be heated to a reformation temperature. Theheat dissipating structure may be fastened to the computing chip usingone or more fasteners.

Some embodiments of the present disclosure include a method for making aSMP TIM pad. A SMP matrix and a thermally conductive filler may be mixedto create a SMP mixture. The SMP mixture may be extruded through a die.The thermally conductive filler in the SMP mixture may be aligned insubstantially the same direction. The SMP mixture may be cured at afirst temperature. The SMP mixture may be sliced into one or more SMPTIM pads.

Some embodiments of the present disclosure include a SMP TIM. The SMPmaterial may include a SMP matrix. The SMP matrix may include a liquidcrystal elastomer. The SMP material may also include a thermallyconductive filler embedded within the SMP matrix. The thermallyconductive filler may include one or more substantially alignedsubcomponents.

FIG. 6 depicts the representative major components of an examplecomputer system 601 that may be used, in accordance with embodiments ofthe present disclosure. It is appreciated that individual components mayvary in complexity, number, type, and\or configuration. The particularexamples disclosed are for example purposes only and are not necessarilythe only such variations. The computer system 601 may comprise aprocessor 610, memory 620, an input/output interface (herein I/O or I/Ointerface) 630, and a main bus 640. The main bus 640 may providecommunication pathways for the other components of the computer system601. In some embodiments, the main bus 640 may connect to othercomponents such as a specialized digital signal processor (notdepicted).

The processor 610 of the computer system 601 may be comprised of one ormore cores 612A, 612B, 612C, 612D (collectively 612). The processor 610may additionally include one or more memory buffers or caches (notdepicted) that provide temporary storage of instructions and data forthe cores 612. The cores 612 may perform instructions on input providedfrom the caches or from the memory 620 and output the result to cachesor the memory. The cores 612 may be comprised of one or more circuitsconfigured to perform one or methods consistent with embodiments of thepresent disclosure. In some embodiments, the computer system 601 maycontain multiple processors 610. In some embodiments, the computersystem 601 may be a single processor 610 with a singular core 612.

The memory 620 of the computer system 601 may include a memorycontroller 622. In some embodiments, the memory 620 may comprise arandom-access semiconductor memory, storage device, or storage medium(either volatile or non-volatile) for storing data and programs. In someembodiments, the memory may be in the form of modules (e.g., dualin-line memory modules). The memory controller 622 may communicate withthe processor 610, facilitating storage and retrieval of information inthe memory 620. The memory controller 622 may communicate with the I/Ointerface 630, facilitating storage and retrieval of input or output inthe memory 620.

The I/O interface 630 may comprise an I/O bus 650, a terminal interface652, a storage interface 654, an I/O device interface 656, and a networkinterface 658. The I/O interface 630 may connect the main bus 640 to theI/O bus 650. The I/O interface 630 may direct instructions and data fromthe processor 610 and memory 620 to the various interfaces of the I/Obus 650. The I/O interface 630 may also direct instructions and datafrom the various interfaces of the I/O bus 650 to the processor 610 andmemory 620. The various interfaces may include the terminal interface652, the storage interface 654, the I/O device interface 656, and thenetwork interface 658. In some embodiments, the various interfaces mayinclude a subset of the aforementioned interfaces (e.g., an embeddedcomputer system in an industrial application may not include theterminal interface 652 and the storage interface 654).

Logic modules throughout the computer system 601—including but notlimited to the memory 620, the processor 610, and the I/O interface630—may communicate failures and changes to one or more components to ahypervisor or operating system (not depicted). The hypervisor or theoperating system may allocate the various resources available in thecomputer system 601 and track the location of data in memory 620 and ofprocesses assigned to various cores 612. In embodiments that combine orrearrange elements, aspects and capabilities of the logic modules may becombined or redistributed. These variations would be apparent to oneskilled in the art.

The computer system 601 may be used to determine the shape memorypolymer matrix (e.g., SMP matrix 102, FIG. 1) and a thermally conductivefiller (e.g., thermally conductive filler 104, FIG. 1) for creating theSMP TIM pad (e.g., SMP TIM 100, FIG. 1) based on thermal requirements ofa computing chip (e.g., computing chip 310, FIG. 3C) and a heatdissipating structure (e.g., heat dissipating structure 350 shown inFIG. 3B). If a thermal requirement of a computing chip requires a highlycompressible TIM, then a first SMP matrix may be selected instead of asecond SMP matrix, which may include a higher compressibility factor atlower pressures. For example, if a compressibility of 30 psi with alower thermal dispersion requirement of a first chip is inputted intothe computer system, the computer system may output a SMP and athermally conductive filler to the user for creating the SMP TIM pad.The SMP may be a LCE as the SMP matrix and a thermally conductive fillerof beryllium oxide. The output may then inform the user of anyquantities required for both the SMP matrix and the thermally conductivefiller. The computer system 601 may also determine a slicing height ofthe original state (e.g., non-deformed shape) of the SMP TIM pad basedon the thermal requirements of the computing chip.

The memory 660 may include a memory controller 622 configured todistribute thermal properties of combinations of SMP matrices andthermally conductive fillers. At least one of the cores of the processor(e.g., the first core 612A) may calculate based on the users SMP TIM padrequirements a list of one or more SMP TIM pad combinations. The usermay input the requirements of the thermal dissipation of the computingchip though the I/O interface 636, and receive the calculated one ormore SMP TIM pad combinations through the terminal interface 632.

The present disclosure may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent disclosure. The computer readable storage medium can be atangible device that can retain and store instructions for use by aninstruction execution device.

The computer readable storage medium may be, for example, but is notlimited to, an electronic storage device, a magnetic storage device, anoptical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present disclosure may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Smalltalk, C++ or the like, andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present disclosure.

Aspects of the present disclosure are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of thedisclosure. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions. These computer readable programinstructions may be provided to a processor of a general purposecomputer, special purpose computer, or other programmable dataprocessing apparatus to produce a machine, such that the instructions,which execute via the processor of the computer or other programmabledata processing apparatus, create means for implementing thefunctions/acts specified in the flowchart and/or block diagram block orblocks. These computer readable program instructions may also be storedin a computer readable storage medium that can direct a computer, aprogrammable data processing apparatus, and/or other devices to functionin a particular manner, such that the computer readable storage mediumhaving instructions stored therein comprises an article of manufactureincluding instructions which implement aspects of the function/actspecified in the flowchart and/or block diagram block or blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present disclosure. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

The descriptions of the various embodiments of the present disclosurehave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

What is claimed is:
 1. A shape memory polymer thermal interface materialincluding: a shape memory polymer matrix, the shape memory polymermatrix including a liquid crystal elastomer; and a thermally conductivefiller embedded within the shape memory polymer matrix, wherein thethermally conductive filler is oriented in a Z-axis direction, wherein afirst height is the Z-axis, wherein the thermally conductive fillerincludes one or more substantially aligned subcomponents, and wherein atleast one subcomponent of the one or more substantially alignedsubcomponents is substantially aligned in a first direction when the atleast one subcomponent is within thirty degrees from perpendicular to anXY-plane, wherein a first length is the X-axis and a first width is theY-axis.
 2. The shape memory polymer thermal interface material of claim1, wherein the substantially aligned subcomponents includeelectromagnetically responsive particles, and wherein theelectromagnetically responsive particles are substantially aligned inthe first direction.
 3. The shape memory polymer thermal interfacematerial of claim 1, wherein the substantially aligned subcomponentsinclude electromagnetically responsive fibers, and wherein theelectromagnetically responsive fibers are substantially aligned in thefirst direction.
 4. The shape memory polymer thermal interface materialof claim 1, wherein the substantially aligned subcomponents includeelectromagnetically responsive particles and electromagneticallyresponsive fibers, and wherein the electromagnetically responsiveparticles and fibers are substantially aligned in the first direction.5. The shape memory polymer thermal interface material of claim 4,wherein the electromagnetically responsive particles and fibers areconfigured to deform to a second direction.
 6. The shape memory polymerthermal interface material of claim 1, wherein the shape memory polymermatrix is configured to expand anisotropically.
 7. The shape memorypolymer thermal interface material of claim 1, wherein the shape memorypolymer matrix is configured to expand isotropically.
 8. The shapememory polymer thermal interface material of claim 1, wherein shapememory polymer matrix includes one or more cross-linking polymernetworks.
 9. The shape memory polymer thermal interface material ofclaim 1, wherein the thermally conductive filler is selected from agroup consisting of: carbon fibers, carbon nanotubes, silicon carbide,beryllium oxide, aluminum nitride, silver, boron nitride, zinc oxide,and aluminum oxide.
 10. The shape memory polymer thermal interfacematerial of claim 1, wherein the shape memory polymer matrix is selectedfrom a group consisting of: polyurethane, polyethylene, polyethyleneterephthalate, polyethylene glycol, and copolyester.
 11. The shapememory polymer thermal interface material of claim 1, wherein the shapememory polymer matrix is a liquid crystal elastomer matrix, wherein thethermally conductive filler materials include carbon fibers andberyllium oxide, and wherein the carbon fibers are substantially alignedin the first direction.